A Field Effect Transistor (FET) is a semiconductor device that controls the electrical conductivity between a source of electric current (source) and a destination of the electrical current (drain). The FET uses a semiconductor structure called a “gate” to create an electric field, which controls the shape and consequently the electrical conductivity of a channel between the source and the drain. The channel is a charge carrier pathway constructed using a semiconductor material.
Many semiconductor devices are planar, i.e., where the semiconductor structures are fabricated on one plane. A non-planar device is a three-dimensional (3D) device where some of the structures are formed above or below a given plane of fabrication.
A “contact” is an electrically conductive structure formed on an externally accessible surface of a semiconductor device. The semiconductor device, such as an FET, can be electrically connected into a circuit via the contacts. A contact of a semiconductor device electrically couples to one or more structures, generally a single structure, within the semiconductor device. Regardless of the planar or non-planar nature of a semiconductor device, such as the FET, various electrical contacts are generally formed or positioned on a single externally accessible surface of the device for the ease of connecting the device in a circuit. For example, in a transistor device, one contact (CB contact) connects to the gate structure in the device, one contact (a CA contact) connects to the source structure in the device, and one contact (another CA contact) connects to the drain structure in the device. Depending on the type of the transistor, additional contacts may be available, e.g., a contact (a TS contact) connecting to the fin in a finFET.
For the purposes of the illustrative embodiments, the orientation of the device is described in a three-dimensional space using X, Y, and Z coordinate system. The plane of fabrication is assumed to be the X-Z plane, with vertical structures above the fabrication plane extending in +Y direction and the vertical structures below the fabrication plane extending in −Y direction. This example orientation is not intended to be limiting. From this disclosure, those of ordinary skill in the art will be able to conceive other orientations of semiconductor devices in which an embodiment described herein can be adapted, and such alternate orientations and adaptations are contemplated within the scope of the illustrative embodiments.